DESCRIPTION: This proposal request funds to develop an ultrasensitive mass spectrometric procedure for the analysis of neurosteroids in tissue samples and microdialysates of select brain areas of freelymoving rats after acute and chronic administration of ethanol, and during alcohol withdrawal. The work in this proposal will first focus on extending the gas chromatographic-mass spectrometric mode of negative chemical ionization of polyfluorinated derivatives to the analysis of the neurosteroids allopregnenolone, pregnenolone and dehydroepiandrosterone in small milligram quantities of tissue from select areas of the brains of control and alcohol treated rats. These neurosteroids have been demonstrated to be synthesized de novo in the rat brain from cholesterol, such that their overall levels in brain are different from, and can be independent of circulating levels of these steroids. Subsequently, these neurosteroids have been implicated in the physiological, emotional, and behavioral responses to stress. Moreover, the anxiolytic and anticonvulsant effects of both ethanol and these neurosteroids have been hypothesized to be mediated in part by elective interactions within the complex family of gamma-aminobutyric acid GABA receptors in the brain. These receptors control the flux of chloride ions in neural membranes, where GABA acts as the primary inhibitory neurotransmitter in the mammalian brain. Neurosteroids and ethanol both augment GABAergic neurotransmission, and because of their common neuropharmacologic actions, it is postulated that neurosteroids influence the development of alcohol abuse and alter the effects of alcohol withdrawal. The results of this research will provide important insights about the role of neurosteroids in alcohol abuse and in the behavioral and neurochemical effects of alcohol withdrawal.